BC30 with 6V6GT's and a 5Y3GT???

[Andyroid]

Hi guys, been using my BC30 for studio recording and its just too loud! I'd like to get power amp breakup at lower volume levels so I've ordered these. I'm pretty sure these valves will just work as direct replacements with out modifications to the amp. But what do you lot think? Will the 15W/30W switch be a problem?

 

Cheers,

Andy

[Andyroid]

LOL, kinda ironic, Ike-e-poo's BC30 breaks up to soon for him and he posted just before me!

I'd like to point out, I don't want to use a power-break (they thin out the tone) and I don't know of any low efficiency speakers that would suit the amp. Probably couldn't afford any anyway and my next speakers will be something like the black mountains. Though I have found what could be a nice schematic for power-scaling, I'm not sure about it though. Take a look, http://www.tone-lizard.com/Marshall_Myths.htm

 

I'm pretty sure that with a cathode biased power stage, all you have to do is reduce the voltage to the plates. Is it really that easy to get 410v down to something like 70v without affecting current draw? how about a switching regulator followed by a linear regulator, on a toggle switch to get full power for gigs, reduced power for recording?

 

Just thoughts,

andy

[twanger]

I went with the THD Yellowjackets and EL84 tubes to drop the output. They function similar to your current tubes but at about 40% - 50% of the output. I do like them but when you do want to crank it up and drive it hard the EL84s just can't deliver like the 6L6s. But for just jammin' at home the El84s work fine for me.

[Andyroid]

Well, they arrived today! Tung-Sol 6V6GT and Mazda 5Y3GT. Can't say its any quieter but...MY GOD! It sounds ... amazing. And I'm not just saying that to justify making my ears ring like thay are doing! It's just the sound I've been after for as long as I can remember. The sag is there giving it great thump, channel 2 gain is best just past 9 o'clock, using phase inverter and power valve distortion mostly. It's kinda like the sound Angus Young had in the 70's but with a touch of AC30. The clean channel now breaks up like it's supposed to, Rolling Stones 'Start Me Up' and beyond!, it's a real amp now!. I thought it was great before valve swap, but now...When I get chance I'll get some audio clips up on the web somewhere, I have a good recording setup.

 

BTW, the Mazda 5Y3GT only has four pins, the stock rectifier (sovtek 5ar4) had 5, with an internally connected pin1, not sure what that means. The schematic doesnt show any connection to pin1, even so I googled like hell for info, didnt find any, decided to be wreckless and fired it up! Working like a charm so far!

 

Happier than Larry,

Andy

 

 

EDIT: Previous power valves were Harma 6L6GC with Harma 5AR4. Did sound sterile by comparison. Stock Sovtek 6L6WGC were dull and muddy.

Mods:V1a and V2a cathode resistors now 1.5k. Phase inverter plate resistors now carbon comp. Mid pot now something like 250k (can't really remember). I think everything else is stock v2006.

[Soaring138]

Hello,

 

the change 6L6WGC Sovtec to EL84 with the VHT 6 special Socket (same fonction as the THD yellow sockets) ist definitly a good way to break up earlier.

After the change, you see that the output power is bigger, but for it you get more drive, more crunch, and your can achieve the breaking point with a smaller level... Better sound at a lower level. Very Good !

 

And one more thing : the change add more compression to your sound, what I like specialy ! :o)

 

Now I'm going to have a look to the preamp tubes...